Catheter Localization via Regional Impedance Calibration
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Solution Overview
Problem
Current position sensing systems within the body face challenges in accurately determining the location of objects like catheters due to artifacts caused by body movements and impedance changes, which affect the reliability of real-time spatial coordinate measurement.
Innovation Solution
A method involving the use of body-electrodes and a mapping-tool to generate calibration-currents and derive relations between these currents and positions, allowing for accurate determination of object location by compensating for impedance changes and body movements, utilizing a combination of electromagnetic and current localization tracking systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If impedance-based position sensing is used within the body, then real-time spatial coordinate measurement is achieved, but measurement precision deteriorates due to artifacts from body movements and impedance changes
Solution Approach 1:
The patent introduces body-electrodes as intermediary elements that establish a stable reference framework on the body surface. These electrodes serve as mediators between the impedance sensing system and the moving internal structures, providing fixed reference points that allow differentiation between body movement artifacts and actual catheter position changes, thereby improving measurement precision without sacrificing reliability
Solution Approach 2:
The system dynamically adjusts and recalibrates impedance parameters based on detected body movements and physiological changes. By continuously monitoring impedance variations and updating calibration data, the system adapts to changing conditions (such as respiration, heartbeats, and body movements), maintaining measurement precision despite the dynamic in-vivo environment
2Measurement precision
If calibration is performed for the entire body, then comprehensive position data is obtained, but device complexity increases due to processing large volumes of data from all regions
Solution Approach 1:
The patent divides the body into multiple discrete regions, each with its own calibration data set. Instead of processing a single large-scale calibration for the entire body, the system performs segmented calibration for each region, reducing the computational burden and data processing complexity while maintaining comprehensive position determination accuracy across all regions
Solution Approach 2:
The system implements region-specific calibration relations tailored to the unique electrical properties and anatomical characteristics of each body region. This local approach allows optimization of calibration parameters for specific areas (such as thorax, abdomen, or limbs) without being constrained by uniform whole-body calibration requirements, thereby reducing overall system complexity while preserving measurement precision
3Measurement precision
If multiple body-electrodes are positioned for comprehensive tracking, then position accuracy improves, but ease of operation deteriorates due to the complexity of electrode placement and calibration
Solution Approach 1:
The body-electrodes are designed with multi-functionality, serving both as impedance sensing elements and as reference markers for position tracking. This universal design eliminates the need for separate electrode systems for different measurement purposes, reducing the overall number of electrodes required and simplifying the placement and calibration process while maintaining high position tracking accuracy
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the accuracy of position tracking within the body by compensating for impedance changes and body movements, improving the precision of object location determination in real-time.
Implementation Method 1
The impedance between the probe and each of the body surface electrodes is measured, and three-dimensional position coordinates of the probe are determined based on the impedance measurements
Implementation Method 2
tracking the mapping-tool at different positions in each of the regions using a location-measuring system
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A method includes positioning body-electrodes in galvanic contact with a body of a patient and positioning a mapping-tool, having a mapping-electrode, in a plurality of regions in the body. The method further includes tracking the mapping-tool at different positions in each of the regions using a location-measuring system, and for each region, generating a respective set of calibration-currents between the body-electrodes and the mapping-electrode at the different positions in the region. A respective relation is derived for each region between the respective set of the calibration-currents and the different positions, and is used in determining the location of an investigation-tool in response to the different respective relations and investigation-tool-currents.